TECHNICAL FIELD
[0001] The present invention relates to a flame-retardant polymer composition comprising
an ethylene/unsaturated ester copolymer, a propylene-based polymer and a filler; an
article comprising the composition; and an electric wire and electric cable comprising
the composition. The present invention also relates to a composition excellent in
the balance among mechanical strength, elongation at break, hardness, flexibility
and heat resistance; an article comprising the composition; and an electric wire and
electric cable having an insulator and/or a sheath comprising the composition.
BACKGROUND ART
[0002] Propylene-based polymers are excellent in heat resistance, mechanical strength and
scratch resistance, and articles obtained therefrom are used in a wide range of applications.
Articles obtained from general resin compositions composed of polypropylene and inorganic
fillers are also excellent in heat resistance and mechanical properties, but are poor
in flexibility and impact resistance. For this reason, ethylene copolymers are primarily
used in applications requiring properties such as flexibility and impact resistance.
However, articles obtained from the ethylene copolymers are poor in scratch resistance
and heat resistance.
[0003] To overcome this problem, an article composed of a propylene-based polymer and an
inorganic filler (flame-retardant) is known as an electric wire and electric cable
or a wire and electric cable harness that requires scratch resistance (Patent Literature
1).
[0004] It is also known that polypropylene is blended with a propylene/butene copolymer,
polyethylene and an inorganic filler (Patent Literature 2).
[0005] It is also known that a propylene-based polymer is blended with an ethylene/α-olefin
random copolymer elastomer or a styrene elastomer together with an inorganic filler
(Patent Literature 3).
[0006] On the other hand, it is known that an ethylene/vinyl acetate copolymer is blended
with polypropylene, a maleic acid-modified polyethylene and a metal hydrate to form
a composition (Patent Literatures 4 to 8).
[0007] Various improvements have been made as described above for thermoplastic polymer
compositions using a propylene-based polymer and an ethylene/vinyl acetate copolymer.
Still, there is demand for a composition further excellent in the balance among mechanical
properties, hardness, flexibility and heat resistance, an article comprising the composition,
and an electric wire and electric cable having an insulator and/or a sheath comprising
the composition.
CITATION LIST
PATENT LITERATURES
SUMMARY OF THE INVENTION
TECHNICAL PROBLEM
[0009] It is an object of the present invention to provide a thermoplastic polymer composition
excellent in the balance among mechanical strength, elongation at break, flexibility
and heat resistance. It is another object of the present invention to provide an article
comprising the composition, and an electric wire and electric cable having an insulator
and/or a sheath comprising the composition.
SOLUTION TO PROBLEM
[0010] The present invention is based on the finding that the combination of an ethylene/vinyl
ester copolymer with a specific propylene-based polymer achieves good filler containability
of a filler, specifically, good dispersibility of an inorganic filler in a thermoplastic
polymer composition, and provides a thermoplastic polymer composition excellent in
the balance among mechanical strength, elongation at break, flexibility and heat resistance.
Further, the present invention is based on the finding that the use of such a specific
thermoplastic polymer composition provides an article excellent in the balance among
mechanical strength, elongation at break, flexibility and heat resistance. The present
invention has been completed based on the findings.
[0011] That is, the present invention relates to a thermoplastic polymer composition comprising
1 to 350 parts by mass of a filler (D) with respect to 100 parts by mass of polymer
components that comprise 50 to 90% by mass of an ethylene/unsaturated ester copolymer
(A) ; 1 to 40% by mass of a propylene-based polymer (B) having a melting point as
measured by differential scanning calorimetry (DSC) of from 120 to 170°C; and 1 to
49% by mass of a propylene-based polymer (C) having a melting point as measured by
differential scanning calorimetry (DSC) of lower than 120°C or not being observed,
provided that the total amount of (A), (B) and (C) is 100% by mass.
[0012] In a preferable embodiment of the present invention, the propylene-based polymers
(C) are a propylene/ethylene random copolymer (C-0), a propylene/C4-20 α-olefin random
copolymer (C-1), and a propylene/ethylene/C4-20 α-olefin random copolymer (C-2), and
have (a) a molecular weight distribution (Mw/Mn) as measured by gel permeation chromatography
(GPC) of 1 to 3.
[0013] In a desirable embodiment of the present invention, the propylene/C4-20 α-olefin
random copolymer (C-1) satisfies the following requirement (b):
(b) the melting point Tm(°C) and the content M (mol%) of a comonomer structural unit
as determined by 13C-NMR spectrum measurement satisfy the equation (1):
wherein Tm is lower than 120°C.
[0014] In a desirable embodiment of the present invention, the propylene/ethylene/C4-20
α-olefin random copolymer (C-2) satisfies the following requirement (n):
(n) the propylene/ethylene/C4-20 α-olefin random copolymer (C-2) contains 40 to 85
mol% of a structural unit derived from propylene, 5 to 30 mol% of a structural unit
derived from ethylene, and 5 to 30 mol% of a structural unit derived from C4-20 α-olefins,
provided that the total amount of the structural unit derived from propylene, the
structural unit derived from ethylene and the structural unit derived from C4-20 α-olefins
is 100 mol%.
[0015] In a desirable embodiment of the present invention, the filler (D) is at least one
filler selected from metal hydroxides, metal carbonates and metal oxides.
[0016] In a desirable embodiment of the present invention, the filler (D) is selected from
at least one filler selected from organic phosphinic acid salts and polyphosphoric
acid compounds.
[0017] In a desirable embodiment of the present invention, the ethylene/unsaturated ester
copolymer (A) is a copolymer of ethylene and a vinyl ester compound, more desirably
a copolymer of ethylene and vinyl acetate.
[0018] In a desirable embodiment of the present invention, the ethylene/unsaturated ester
copolymer (A) is a copolymer of ethylene and a vinyl ester compound, more desirably
a copolymer of ethylene and vinyl acetate that has a vinyl acetate content of from
25% by mass and up to 50% by mass.
[0019] In another embodiment of the present invention, these thermoplastic polymer compositions
further comprise a modified olefin polymer (E), wherein the proportion of a vinyl
compound having a polar group according to the modification is 0.01 to 10 parts by
mass based on 100 parts by mass of the total of (A), (B), (C) and (E).
[0020] The present invention further relates to an article comprising the thermoplastic
polymer composition, and the article relates to an insulator of an electric wire and
electric cable or an electric wire and electric cable sheath.
ADVANTAGEOUS EFFECTS OF THE INVENTION
[0021] The thermoplastic polymer composition of the present invention provides performance
excellent in the balance among mechanical strength, elongation at break, flexibility
and heat resistance, and is widely applicable to articles, particularly suitable for
electric wires and electric cables and the like.
DESCRIPTION OF EMBODIMENTS
[0022] Hereinafter, the thermoplastic polymer composition of the present invention is described.
Ethylene/unsaturated ester copolymer (A)
[0023] An example of the ethylene/unsaturated ester copolymer (A) used in the thermoplastic
polymer composition of the present invention is a copolymer of ethylene and a vinyl
ester such as vinyl acetate and vinyl propionate, or a copolymer of ethylene and an
alkyl ester having carbon atoms of about 20 or less of an unsaturated carboxylic acid
such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid,
itaconic acid and itaconic anhydride. Specific examples of the copolymers include
copolymers of ethylene and unsaturated carboxylic acid esters such as methyl acrylate,
ethyl acrylate, isopropyl acrylate, n-propyl acrylate, isobutyl acrylate, n-butyl
acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isobutyl
methacrylate, n-butyl methacrylate, glycidyl methacrylate, dimethyl maleate and diethyl
maleate.
[0024] In addition to being the binary copolymers as described above, the ethylene/unsaturated
ester copolymer (A) may be a multicomponent copolymer obtained by copolymerizing ethylene
and two or more kinds of compounds selected from the above unsaturated ester compounds.
Furthermore, as long as the properties of the ethylene/unsaturated ester copolymer
are not substantially changed, other polar monomers may be copolymerized in a small
amount, such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic
anhydride, itaconic anhydride and carbon monoxide.
[0025] In the present invention, among these, a copolymer of ethylene and a vinyl ester
compound is preferable, examples of which include ethylene/vinyl acetate copolymer
and ethylene/vinyl propionate copolymer.
[0026] In the present invention, the proportion of the unsaturated ester compound unit in
the ethylene/unsaturated ester is usually 5 to 70% by mass, more preferably 15 to
60% by mass, still more preferably 25 to 50% by mass. When the proportion of the unsaturated
ester compound is within these ranges, the balance between mechanical strength and
flame retardance is excellent. If the proportion of the unsaturated ester compound
is less than 15% by mass, flame retardance tends to be reduced. If the proportion
of the unsaturated ester compound is more than 60% by mass, mechanical strength tends
to be reduced.
[0027] The ethylene/unsaturated ester copolymer (A) used in the present invention preferably
has a melt flow rate (190°C, 2160 g load: in accordance with JIS K7210-99) of 0.1
to 50 g/10 min, particularly preferably 0. 5 to 10 g/10 min, in view of properties,
processability and the like of the resulting composition.
[0028] The ethylene/unsaturated ester copolymer (A) may be obtained by performing radical
copolymerization of ethylene and an unsaturated ester compound at high temperature
under high pressure.
[0029] For example, a copolymer with good random property produced by high-pressure radical
polymerization process using a common autoclave method may be used.
Propylene-based polymer (B)
[0030] An example of the propylene-based polymer (B) used in the present invention is a
propylene homopolymer or a copolymer of propylene and at least one C2-20 α-olefin
excluding propylene.
[0031] Examples of the C2-20 α-olefin excluding propylene include ethylene, 1-butene, 1-pentene,
1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene,
1-octadecene and 1-eicosene. Preferred is ethylene or a C4-10 α-olefin. These α-olefins
may form a random copolymer or a block copolymer with propylene.
[0032] The structural unit derived from these α-olefins may be contained in an amount of
not more than 35 mol%, preferably not more than 30 mol%, in all the structural units
of the propylene-based polymer (B).
[0033] The propylene-based polymer (B) usually has a melt flow rate as measured at a temperature
of 230°C under a load of 2.16 kg in accordance with ASTM D 1238 (MFR) of 0.01 to 1000
g/10 min, preferably 0.05 to 100 g/10 min, more preferably 0.1 to 50 g/10 min.
[0034] The propylene-based polymer (B) used in the present invention has a melting point
as measured by differential scanning calorimetry (DSC) of from 120 to 170°C, preferably
125 to 165°C.
[0035] The propylene-based polymer (B) may have an isotactic structure or a syndiotactic
structure, but preferably has an isotactic structure in terms of heat resistance and
the like.
[0036] As required, a plurality of propylene-based polymers (B) may be used in combination:
for example, two or more kinds of components differing in melting point and rigidity
may be used.
[0037] In order to obtain desired properties, the propylene-based polymer (B) may be selected
from:
homopolypropylene excellent in heat resistance (usually, a known polymer containing
not more than 3 mol% of a copolymerizable component other than propylene),
block polypropylene excellent in the balance between heat resistance and impact resistance
(usually, a known polymer containing 3 to 30% by mass of a n-decane soluble component),
and
random polypropylene excellent in the balance between flexibility and transparency
(usually, a known polymer having a melting peak temperature as measured by differential
scanning calorimetry (DSC) of not lower than 120°C, preferably 125°C to 150°C). These
may be used in combination.
[0038] The propylene-based polymer (B) may be produced by polymerizing propylene or by
copolymerizing propylene and another olefin for example with the use of a Ziegler
catalyst system comprising a solid catalyst component containing magnesium, titanium,
a halogen and an electron donor as an essential component, an organoaluminum compound
and an electron donor, or with the use of a metallocene catalyst system using a metallocene
compound as a catalyst component.
Propylene-based polymer (C)
[0039] An example of the propylene-based polymer (C) used in the present invention is a
propylene homopolymer or a copolymer of a propylene and at least one C2-20 olefin
excluding propylene. The C2-20 α-olefins excluding propylene may be similar to those
mentioned for the propylene-based polymer (B), and preferable ranges thereof may be
similar to those mentioned for the propylene-based polymer (B). These α-olefins may
form a random copolymer or a block copolymer with propylene.
[0040] The propylene-based polymer (C) contains a structural unit derived from propylene
usually in an amount of 40 to 100 mol%, preferably 40 to 99 mol%, more preferably
40 to 92 mol%, still more preferably 50 to 90 mol%; and a structural unit derived
from C2-20 α-olefins excluding propylene used as a comonomer usually in an amount
of 0 to 60 mol%, preferably 1 to 60 mol%, more preferably 8 to 60 mol%, still more
preferably 10 to 50 mol%, provided that the total amount of propylene and the C2-20
α-olefin is 100 mol%.
[0041] The propylene-based polymer (C) used in the present invention usually has a melt
flow rate (MFR, ASTM D1238, temperature 230°C, under a load of 2.16 kg) of 0.1 to
50 g/10 min. The propylene-based polymer (C) has a melting point as measured by differential
scanning calorimetry (DSC) of lower than 120°C, more preferably from 40 °C to lower
than 110°C, still more preferably 60°C to 100°C. In another embodiment, the propylene-based
polymer (C) preferably has a melting point that is not observed.
[0042] Here, the melting point not being observed means that the crystal melting peak having
a crystal heat of fusion of not less than 1 J/g is not observed in the range of from
-150 to 200°C. Measurement conditions are as described in Examples.
[0043] The propylene-based polymer (C) usually has an intrinsic viscosity [η] as measured
in decalin at 135 °C of 0.01 to 10 dl/g, preferably 0.05 to 10 dl/g. The propylene-based
polymer (C) preferably has a triad tacticity (mm fraction) as measured by
13C-NMR of 85% or more, more preferably 85 to 97.5%, still more preferably 87 to 97%,
particularly preferably 90 to 97%. When the triad tacticity (mm fraction) is within
these ranges, in particular the balance between flexibility and mechanical strength
is excellent, and thus these ranges are preferred in the present invention. The mm
fraction can be measured by a method described in page 21, line 7 to page 26, line
6 of
WO 2004-087775.
[0044] The propylene-based polymer (C) may be produced by a method which is not particularly
limited, but may be produced, for example, by polymerizing propylene or by copolymerizing
propylene and another α-olefin in the presence of a known catalyst capable of polymerizing
α-olefins so as to have stereoregularity, i.e., an isotactic structure or a syndiotactic
structure, for example, a catalyst containing a solid titanium component and an organic
metal compound as a main component, or a metallocene catalyst using a metallocene
compound as a catalyst component. The propylene-based polymer (C) may be produced
by polymerizing propylene or by copolymerizing propylene and another α-olefin in the
presence of a known catalyst capable of polymerizing α-olefins so as to have an atactic
structure. The propylene-based polymer (C) is preferably obtained by copolymerizing
propylene and a C2-20 α-olefin excluding propylene in the presence of a metallocene
catalyst, as is described later.
[0045] A specific example of the propylene-based polymer (C) having features as described
above is at least one selected from a propylene/ethylene random copolymer (C-0), a
propylene/C4-20 α-olefin random copolymer (C-1) and a propylene/ethylene/C4-20 α-olefin
random copolymer (C-2).
[0046] The use of the propylene/ethylene random copolymer (C-0) or the propylene/C4-20 α-olefin
random copolymer (C-1), for example allows for exhibiting the compatibility with a
polypropylene crystalline component contained in the propylene-based polymer (B),
and leads to the provision of a thermoplastic polymer composition further excellent
in mechanical strength, elongation at break, and scratch resistance.
[0047] The propylene/ethylene/C4-20 α-olefin random copolymer (C-2) also has compatibility
with a crystalline component of polypropylene, as is the case with the propylene/C4-20
α-olefin random copolymer (C-1). The use of the propylene/ethylene/C4-20 α-olefin
random copolymer (C-2) provides a thermoplastic polymer resin composition further
excellent in flexibility, elongation at break and scratch resistance.
[0048] The propylene/ethylene random copolymer (C-0), the propylene/C4-20 α-olefin random
copolymer (C-1) and the propylene/ethylene/C4-20 α-olefin random copolymer (C-2),
each of which is preferably used in the present invention, desirably have (a) a molecular
weight distribution (Mw/Mn) as measured by gel permeation chromatography (GPC) of
1 to 3.
Propylene/ethylene random copolymer (C-0)
[0049] The propylene/ethylene random copolymer (C-0) preferably used in the present invention
is a random copolymer obtained by randomly copolymerizing propylene and ethylene,
and contains a structural unit derived from propylene usually in an amount of 50 to
95 mol%, preferably 55 to 90 mol%, more preferably 60 to 88 mol%; and a structural
unit derived from ethylene used as a comonomer usually in an amount of 5 to 50 mol%,
preferably 10 to 45 mol%, more preferably 12 to 40 mol%, provided that the total amount
of propylene and ethylene is 100 mol%.
Propylene/C4-20 α-olefin random copolymer (C-1)
[0050] An example of the propylene/C4-20 α-olefin random copolymer (C-1) preferably used
in the present invention is a copolymer of propylene and at least one C4-20 α-olefin
excluding propylene. Examples of the C4-20 α-olefin excluding propylene include 1-butene,
1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene,
1-hexadecene, 1-octadecene and 1-eicosene. Among the propylene/C4-20 α-olefin random
copolymers (C-1), a preferred propylene/C4-20 α-olefin random copolymer (C-1) satisfies
the following requirement (b):
(b) the melting point Tm (°C) and the content M (mol%) of a comonomer structural unit
as determined by 13C-NMR spectrum measurement satisfy the equation (1):
wherein Tm is lower than 120°C, preferably not higher than 100°C.
[0051] The melting point Tm of the propylene/C4-20 α-olefin random copolymer (C-1) is measured
by DSC as follows: a sample is put in an aluminum pan, and heated at 100 °C/min to
200 °C, kept at 200 °C for 5 minutes, and then cooled at 10 °C /min to -150 °C and
thereafter heated at 10°C/min to 200°C; a temperature of an endothermic peak observed
during the second heating is given as a melting point Tm. The propylene/C4-20 α-olefin
random copolymer (C-1) usually has a melting point Tm of lower than 120°C, preferably
not higher than 100°C, more preferably 40 to 95°C, still more preferably 50 to 90°C.
When the melting point Tm is within these ranges, an article excellent particularly
in the balance between flexibility and strength is obtained, and moreover, the resulting
article has a surface with suppressed tackiness, and thus the article comprising the
composition of the present invention is easy to apply.
[0052] In a preferable embodiment, the propylene/C4-20 α-olefin random copolymer (C-1) further
has a (c) crystallinity as measured by X-ray diffraction of not higher than 40%, more
preferably not higher than 35%.
[0053] The propylene/C4-20 α-olefin random copolymer (C-1) contains a structural unit derived
from C4-20 α-olefins preferably in an amount of 5 to 50 mol%, more preferably 10 to
35 mol%. In particular, the C4-20 α-olefin is preferably 1-butene.
[0054] Such a propylene-based polymer may be obtained by a method described in, for example,
WO 2004/87775.
Propylene/ethylene/C4-20 α-olefin random copolymer (C-2)
[0055] An example of the propylene/ethylene/C4-20 α-olefin random copolymer (C-2) preferably
used in the present invention is a copolymer of propylene, ethylene and at least one
C4-20 α-olefin excluding propylene. As the C4-20 α-olefin excluding propylene, those
mentioned for the propylene/C4-20 α-olefin random copolymer (C-1) can be mentioned.
[0056] The propylene/ethylene/C4-20 α-olefin random copolymer (C-2) suitably used in the
present invention satisfies the following requirement (n):
(n) the propylene/ethylene/C4-20 α-olefin random copolymer (C-2) contains 40 to 85
mol% of a structural unit derived from propylene, 5 to 30 mol% of a structural unit
derived from ethylene, 5 to 30 mol% of a structural unit derived from C4-20 α-olefins,
provided that the total amount of the structural unit derived from propylene, the
structural unit derived from ethylene and the structural unit derived from C4-20 α-olefins
is 100 mol%. The total amount of the structural unit derived from ethylene and the
structural unit derived from C4-20 α-olefins is preferably 60 to 15 mol%.
[0057] It is desirable that the propylene/ethylene/C4-20 α-olefin random copolymer (C-2)
further satisfies at least one of the following requirements (o) and (p), more preferably
both of the following requirements (o) and (p):
(o) Shore A hardness is 30 to 90, preferably 35 to 60.
(p) The crystallinity as measured by X-ray diffraction is not higher than 20%, preferably
not higher than 10%.
[0058] The propylene/ethylene/C4-20 α-olefin random copolymer (C-2) desirably has a melting
point Tm as measured by DSC of not higher than 50°C or not being observed. The melting
point not being observed is more preferable. The melting point can be measured in
the same manner as described for the copolymer (C-1).
[0059] The amount of the propylene component and the amount of the other comonomer components
are described in more detail as follows. It is desirable that the structural unit
derived from propylene is contained preferably in an amount of 60 to 82 mol%, more
preferably 61 to 75 mol%; the structural unit derived from ethylene is contained preferably
in an amount of 8 to 15 mol%, more preferably 10 to 14 mol%; and the structural unit
derived from C4-20 α-olefins is contained preferably in an amount of 10 to 25 mol%,
more preferably 15 to 25 mol%, provided that the total amount of the structural unit
derived from propylene, the structural unit derived from ethylene and the structural
unit derived from C4-20 α-olefins is 100 mol%. In particular, the C4-20 α-olefin is
preferably 1-butene.
[0060] The propylene/ethylene/α-olefin random copolymer (C-2) may be obtained by a method
described in, for example,
WO 2004/87775.
[0061] In the present invention, the use of the propylene/ethylene/C4-20 α-olefin random
copolymer (C-2) provides an article having further improved flexibility, larger elongation
at break and lower embrittlement-temperature in low temperature environment. For example,
in the case where this article is an electric wire and electric cable, even when exposed
to low temperature, the electric wire and electric cable coating hardly undergoes
cracking.
[0062] The propylene-based polymer (C), specific examples of which include the propylene/ethylene
random copolymer (C-0), the propylene/C4-20 α-olefin random copolymer (C-1) and the
propylene/ethylene/C4-20 α-olefin random copolymer (C-2), may be a polymer obtained
by modifying part of or whole of the propylene-based polymer (C) with a vinyl compound
having a polar group described later, as required.
[0063] The vinyl compound having a polar group and the modification method that are employable
in this case may be a vinyl compound having a polar group and a modification method
that are employed for a modified olefin polymer (E) described later.
Filler (D)
[0064] The filler (D) used in the present invention is not particularly limited, and may
be various fillers including general inorganic fillers and organic fillers that serve
as flame-retardants, molding assistants, slip agent and the like.
[0065] Among these, when inorganic fillers are used, at least one inorganic filler selected
from metal hydroxides, metal carbonates and metal oxides is preferred.
[0066] The metal hydroxides used in the present invention, which are not particularly limited,
include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide,
manganese hydroxide, zinc hydroxide and hydrotalcite and mixtures of these metal hydroxides.
Preferable metal hydroxides include magnesium hydroxide and a mixture of magnesium
hydroxide and a metal hydroxide other than magnesium hydroxide; and aluminum hydroxide
and a mixture of aluminum hydroxide and a metal hydroxide other than aluminum hydroxide,
e.g., a mixture of aluminum hydroxide and magnesium hydroxide.
[0067] The metal carbonates used in the present invention, which are not particularly limited,
include calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate and
mixtures of these metal carbonates.
[0068] The metal oxides used in the present invention, which are not particularly limited,
include alumina, zinc oxide, titanium oxide, magnesium oxide, calcium oxide and mixtures
of these metal oxides.
[0069] Among these, magnesium hydroxide, aluminum hydroxide, basic magnesium carbonate and
hydrotalcite are preferable, and the use of magnesium hydroxide and/or aluminum hydroxide
is preferable.
[0070] As the inorganic fillers, those usually having an average particle diameter of about
0.05 to 20 micrometer (µm), preferably about 0.1 to 5 micrometer (µm) are employable.
In order to improve the dispersibility with respect to the polymer components of the
composition, those having their surfaces treated with a surface-treating agent are
preferably used. Examples of the surface-treating agent include alkali metal salts
of higher fatty acids such as sodium caprate, sodium laurate, sodium myristate, sodium
palmitate, sodium stearate, potassium stearate, sodium oleate, potassium oleate and
sodium linoleate; higher fatty acids such as capric acid, lauric acid, myristic acid,
palmitin, stearic acid, oleic acid and linoleic acid; fatty acid amides; fatty acid
esters; higher aliphatic alcohols; titanium coupling agents such as isopropyltriisostearoyl
titanate, isopropyltris(dioctylpyrophosphate)titanate and tetraisopropylbis(dioctylphosphite)titanate;
silane coupling agents such as vinyl triethoxysilane, γ-methacryloxypropyltrimethoxysilane,
γ-glycidoxypropyltrimethoxysilane; silicone oils; and various phosphoric acid esters.
[0071] Other examples of the filler (D) that are optionally used in the present invention
include organic and inorganic flame retardance imparting agents (flame-retardants
and flame-retardant assistants).
[0072] Usually, these organic and inorganic flame retardance imparting agents (flame-retardants
and flame-retardant assistants) alone are used, independently of the filler (D) including
metal hydroxides, metal carbonates and metal oxides as described above. However, as
required, the filler (D) such as metal hydroxides, metal carbonates and metal oxides
may be used in combination with the organic and inorganic flame retardance imparting
agents (flame-retardants and flame-retardant assistants).
[0073] The organic and inorganic flame retardance imparting agents (flame-retardants and
flame-retardant assistants) as other examples of the filler (D) are described below.
[0074] Examples of the flame retardance imparting agents that are employed include bromine-based
flame retardance imparting agents; phosphorus-based flame retardance imparting agents
such as red phosphorus, phosphoric acid esters, phosphoric acid amides and organic
phosphine oxides; ammonium polyphosphate; nitrogen-based flame retardance imparting
agents such as phosphazene, triazine and melamine cyanurate; metal salt-based flame
retardance imparting agents such as alkali metal salts of polystyrene sulfonic acid;
inorganic flame retardance imparting agents such as zinc borate and zinc stannate;
and silicone-based flame retardance imparting agents such as silicone resins and silicone
oils.
[0075] These flame retardance imparting agents may be used singly, or two or more kinds
thereof may be used in combination, as required.
[0076] Among these, the phosphorus-containing flame retardance imparting agents are preferable,
and examples thereof include phosphorus-based flame retardance imparting agents including
red phosphorus, phosphoric acid esters, phosphoric acid amides and organic phosphinic
acid salts, and ammonium polyphosphate (APP) as described above. Known phosphorus-containing
flame retardance imparting agents used as a flame-retardant are employable. Specific
examples thereof include ammonium phosphate, melamine pyrophosphate, ammonium polyphosphate
and melamine polyphosphate, with polyphosphoric acid compounds such as melamine pyrophosphate
and melamine polyphosphate being preferable. These phosphorus-containing flame retardance
imparting agents include modified phosphoric acid compounds that have their surfaces
modified or coated with melamine, a melamine resin, a fluoropolymer or the like; and
melamine-crosslinked phosphoric acid compounds obtained by crosslinking with melamine.
These phosphorus-containing flame retardance imparting agents may be used singly,
two or more kinds thereof may be used in combination.
[0077] As the nitrogen-based flame retardance imparting agents, compounds containing a triazine
ring can be mentioned. Examples thereof include compounds generally known as a flame-retardant,
such as melamine, ammeline, melam, benzoguanamine, acetoguanamine, phthalodiguanamine,
melaminecyanurate, melamine pyrophosphate, butylenediguanamine, norbornenediguanamine,
methylenedimelamine, ethylenedimelamine, trimethylenedimelamine, tetramethylenedimelamine,
hexamethylenedimelamine and 1,3-hexylenedimelamine. Among these, melaminecyanurate
is preferable.
[0078] The amount of the flame retardance imparting agents such as the compounds having
a triazine ring may be the blending proportion of the filler (D) as described above,
but is 0.1 to 100 parts by mass, more preferably 0.1 to 80 parts by mass, still more
preferably 5 to 60 parts by mass based on 100 parts by mass of the total of the polymer
components (A), (B) and (C) and optionally (E) of the present invention. If the blending
amount is less than 0.1 part by mass, the generation of a combustion inert gas (nitrogen
gas) from this compound tends to be insufficient, and the synergistic effect with
another flame retardance imparting agent tends to be insufficient. On the other hand,
even if the amount is more than 100 parts by mass, there is not much difference in
flame retardance effect, and rather, such an amount may adversely affect molding processability
or mechanical properties and the like of the resulting article, and thus is not desirable.
[0079] In the embodiment using phosphorus-containing flame retardance imparting agents,
the amount of the phosphorus-containing flame retardance imparting agent is 15 to
100 parts by mass, more preferably 30 to 90 parts by mass, still more preferably 35
to 80 parts by mass, based on 100 parts by mass of the total of the polymer components
(A), (B) and (C), and optionally (E) of the present invention.
[0080] The inorganic flame retardance imparting agents include antimony compounds such as
antimony trioxide, antimony pentaoxide and sodium antimonate; zinc compounds such
as zinc sulfate, zinc stannate, zinc hydroxystannate and zinc borate; iron compounds
such as ferrous hydroxyzincate and ferric oxide; tin compounds such as metastannic
acid, stannous oxide and stannic oxide; and tungsten compounds such as metal salts
of tungstic acid, composite oxide acids of tungsten and a metalloid; zirconium compounds;
and hydrotalcites; these may be surface-treated with a fatty acid, a silane coupling
agent or the like. Among these, zinc compounds, in particular at least one zinc salt
selected from zinc stannate, zinc hydroxystannate and zinc borate, are preferable.
The blending of these compounds further improves flame retardance, and moreover increases
a shell formation rate during combustion and leads to more solid formation of the
shell. It is preferred that the zinc borate, zinc hydroxystannate and zinc stannate
each have an average particle diameter of not more than 5 micrometer (µm), more preferably
not more than 3 micrometer (µm). Examples of the zinc borate include ALCANEX FRC-500
(2ZnO/3B
20
3·3.5H
20), FRC-600 (product name, manufactured by MIZUSAWA INDUSTRIAL CHEMICALS, LTD.). Examples
of the zinc stannate (ZnSnO
3) and zinc hydroxystannate (ZnSn(OH)
6) include ALCANEX ZS and ALCANEX ZHS (product name, manufactured by MIZUSAWA INDUSTRIAL
CHEMICALS, LTD.).
[0081] Examples of the silicone-based flame retardance imparting agents include silicone
resins and silicone oils. Examples of the silicone resins include resins having three-dimensional
net-like structure formed by combining structures of any of SiO
2, RSiO
3/2, R
2SiO and R
3SiO
1/2, wherein R is an alkyl group such as methyl group, ethyl group and propyl group,
or an aromatic group such as phenyl group and benzyl group, or a substituent formed
when any of the above substituents has a vinyl group. Examples thereof include silicone
oils such as dimethyl silicone oil and methylphenyl silicone oil; modified silicone
oils such as epoxy-modified silicone oil, alkyl-modified silicone oil, amino-modified
silicone oil, carboxyl-modified silicone oil, alcohol-modified silicone oil and ether-modified
silicone oil; silicone rubbers such as dimethyl polysiloxane rubber and methyl vinyl
polysiloxane rubber; silicone resins such as methyl silicone resin and ethyl silicone
resin; and fine particulate silicone powder (Si powder).
[0082] The silicone powder (Si powder) and the like as described above serve also as a molding
assistant and a slip agent.
[0083] In the embodiment using the silicone-based flame retardance imparting agents of the
present invention, the amount of the silicone-based flame retardance imparting agent
is 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, still more preferably
2 to 15 parts by mass, based on 100 parts by mass of the total of the polymer components
(A), (B), (C) and optionally (E) of the present invention.
[0084] As described above, the fillers (D) used in the present invention include organic
fillers, inorganic fillers, various flame retardance imparting agents, molding assistants
and slip agents, and at least one of these is used as required.
[0085] The proportion of the filler (D) is preferably 1 to 350 parts by mass, more preferably
100 to 300 parts by mass, based on 100 parts by mass of the total of (A), (B) and
(C). This allows the thermoplastic polymer composition to achieve a balance among
flame retardance, mechanical properties and flexibility.
Modified olefin polymer (E)
[0086] In the present invention, a modified olefin polymer (E) is preferably used together
with the ethylene/unsaturated ester copolymer (A), the propylene-based polymer (B)
and the propylene-based polymer (C).
[0087] The modified olefin polymer (E) is a modified product of a polymer other than the
ethylene/unsaturated ester copolymer (A), the propylene-based polymer (B) and the
propylene-based polymer (C), with examples thereof including modified polyolefins
such as modified polyethylene, modified polypropylene, modified polybutene, modified
poly(4-methylpentene), modified ethylene/α-olefin copolymers, e.g., modified ethylene/propylene
copolymer and modified ethylene/1-butene copolymer, modified propylene/α-olefin copolymers,
e.g., modified propylene/1-butene copolymer, modified propylene/ethylene/α-olefin
copolymer wherein the α-olefin is selected from C4-20 α-olefins, e.g., modified propylene/ethylene/1-butene
copolymer; and modified ethylene unsaturated ester copolymer such as modified ethylene
vinyl acetate copolymer and modified ethylene acrylic acid ester copolymers.
[0088] These can be produced by graft modifying unmodified polymers.
[0089] Examples of the vinyl compound having a polar group employed for the modification
include vinyl compounds that have an oxygen-containing group such as an acid, an acid
anhydride, an ester, an alcohol, an epoxy and an ether; vinyl compounds that have
a nitrogen-containing group such as an isocyanate and an amide; and vinyl compounds
having a silicon-containing group such as a vinylsilane.
[0090] Among these, the vinyl compounds that have an oxygen-containing group are preferable,
and specifically preferred are unsaturated epoxy monomers, unsaturated carboxylic
acids and derivatives thereof. Examples of the unsaturated epoxy monomers include
unsaturated glycidyl ethers and unsaturated glycidyl esters (for example, glycidyl
methacrylate). Examples of the unsaturated carboxylic acids include acrylic acid,
maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid,
crotonic acid, isocrotonic acid and nadic acid™ (endo-cis-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic
acid).
[0091] Examples of the derivatives of the unsaturated carboxylic acids include acid halide
compounds, amide compounds, imide compounds, acid anhydrides and ester compounds of
the above unsaturated carboxylic acids. Specific examples thereof include malenyl
chloride, maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl
maleate and glycidyl maleate.
[0092] Among these, the unsaturated dicarboxylic acids and acid anhydrides thereof are more
preferable, and particularly preferred are maleic acid, nadic acid™ and acid anhydrides
thereof.
[0093] The graft position of the unsaturated carboxylic acids or derivatives thereof to
be grafted to the above unmodified olefin polymers is not particularly limited, as
long as the unsaturated carboxylic acids or derivatives thereof are bonded to any
carbon atom of the olefin polymers.
[0094] The modified olefin polymer (E) as described above may be prepared by various known
methods, for example, methods as described below.
- (1) a method in which the above unmodified olefin polymer is molten with an extruder
or the like, and an unsaturated carboxylic acid or its derivative is added thereto,
to thereby perform graft copolymerization; and
- (2) a method in which the above unmodified olefin polymer is dissolved in a solvent,
and an unsaturated carboxylic acid or its derivative is added thereto, to thereby
perform graft copolymerization.
[0095] In any of the above methods, graft reaction is performed preferably in the presence
of a radical initiator for efficient graft copolymerization of the above graft monomers
such as unsaturated carboxylic acids.
[0096] Employable examples of the radical initiator include organic peroxides and azo compounds.
Examples of the organic peroxides include benzoyl peroxide, dichlorobenzoyl peroxide,
and dicumyl peroxide. Examples of the azo compounds include azobisisobutylnitrile
and dimethyl azoisobutyrate.
[0097] Specific examples of the radical initiators that are preferably used include dialkyl
peroxides such as dicumyl peroxide, di-tert-butylperoxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexine-3,2,5-dimethyl-2,
5-di(tert-butylperoxy)hexane and 1,4-bis(tert-butylperoxyisopropyl)benzene.
[0098] The radical initiator is used usually in an amount of 0.001 to 1 part by mass, preferably
0.003 to 0.5 part by mass, still more preferably 0.05 to 0.3 part by mass, based on
100 parts by mass of the unmodified olefin polymer.
[0099] In the graft reaction employing the radical initiators, or in the graft reaction
not employing the radical initiators, the reaction temperature is usually 60 to 350°C,
preferably 150 to 300°C.
[0100] The graft amount of the vinyl compound having a polar group in the modified olefin
polymer (E) thus obtained is usually 0.01 to 10% by mass, preferably 0.05 to 5% by
mass, provided that the mass of the modified olefin polymer is 100% by mass.
[0101] In the present invention, the use of the modified olefin polymer (E) as described
above particularly increases the interaction between the filler (D) and the polymer
components, resulting in the provision of a thermoplastic polymer composition excellent
in the balance among mechanical strength, elongation at break, flexibility and heat
resistance.
[0102] Instead of adding the modified olefin polymer (E) or together with the modified olefin
polymer (E), at least part of or whole of the polymers (A), (B) and (C) may be modified.
In this case, too, similar effects are obtained.
[0103] In this case, the modification may be performed in accordance with the description
set forth for the olefin polymer (E) as described above. In the present invention,
the polymers (A), (B) and (C) include a modified polymer (A), a modified polymer (B)
and a modified polymer (C), respectively, which are obtained by modifying part of
or whole of the polymers (A), (B) and (C).
Thermoplastic polymer composition
[0104] The thermoplastic polymer composition of the present invention comprises 1 to 350
parts by mass of the filler (D) with respect to 100 parts by mass of the polymer components
comprising 50 to 90% by mass of the ethylene/unsaturated ester copolymer (A) ; 1 to
40% by mass of the propylene-based polymer (B) having a melting point as measured
by differential scanning calorimetry (DSC) of from 120 to 170°C; and 1 to 49% by mass
of the propylene-based polymer (C) having a melting point as measured by differential
scanning calorimetry (DSC) of lower than 120°C or not being observed, provided that
the total amount of (A), (B) and (C) is 100% by mass.
[0105] Among the thermoplastic polymer compositions of the present invention, a thermoplastic
polymer composition according to a preferred embodiment comprises 100 to 300 parts
by mass of the filler (D) with respect to 100 parts by mass of the polymer components
comprising the ethylene/unsaturated ester copolymer (A) in an amount of 52 to 90%
by mass, more preferably 55 to 90% by mass, still more preferably 55 to 85% by mass;
the propylene-based polymer (B) having a melting point as measured by differential
scanning calorimetry (DSC) of from 120 to 170°C in an amount of 1 to 30% by mass,
more preferably 1 to 20% by mass, still more preferably 1 to 10% by mass; and the
propylene-based polymer (C) having a melting point as measured by differential scanning
calorimetry (DSC) of lower than 120°C or not being observed in an amount of 5 to 49%
by mass, more preferably 9 to 40% by mass, still more preferably 9 to 35% by mass,
provided that the total amount of (A), (B) and (C) is 100% by mass.
[0106] The polymer components containing more than 40% by mass of the propylene-based polymer
(B) lead to reduced flexibility, elongation at break and flame retardance. The polymer
components containing more than 49% by mass of the propylene-based polymer (C) lead
to reduced flame retardance.
[0107] When the modified olefin polymer (E) is used in combination, it is desirable that
the modified olefin polymer (E) is used in such a manner that the proportion of the
modified olefin polymer (E) in the thermoplastic polymer composition is controlled
such that the proportion of the vinyl compound having a polar group according to the
modification is 0.01 to 10 parts by mass based on 100 parts by mass of the total of
the ethylene/unsaturated ester copolymer (A), the propylene-based polymer (B), the
propylene-based polymer (C) and the modified olefin polymer (E).
[0108] When part of or whole of the polymers (A), (B) and (C) is modified with the vinyl
compound having a polar group, the amount of the vinyl compound having a polar group
contained in such polymers is included in the above-mentioned graft amount.
[0109] In general, a polymer other than the polymer components (A), (B) and (C) is previously
graft-modified with a vinyl compound having a polar group, to give the modified olefin
polymer (E). In this case, the modified olefin polymer (E) in which the amount of
the vinyl compound having a polar group is 0.01 to 10% by mass, preferably 0.05 to
5% by mass provided that the mass of the modified olefin polymer is 100% by mass is
incorporated in an amount of 2 to 30% by mass, preferably 3 to 20% by mass of the
polymer components comprising (A), (B), (C) and (E) of the thermoplastic polymer composition
of the present invention, provided that the total amount of (A), (B), (C) and (E)
is 100% by mass.
[0110] When the polymer component (E) is not used and any of the polymer components (A),
(B) and (C) of the present invention is partly or wholly graft-modified, the modification
is performed in such a manner that the proportion of the vinyl compound having a polar
group according to the modification is 0.01 to 10 parts by mass based on 100 parts
by mass of the total of the polymers (A), (B) and (C).
[0111] The ratios among (A), (B) and (C) in the embodiment using the modified olefin copolymer
(E) are similar to those in the embodiment not using the modified olefin copolymer
(E). The proportion of the amount of the filler (D) is 1 to 350 parts by mass, more
preferably 100 to 300 parts by mass, based on 100 parts by mass of the total of (A),
(B), (C) and (E).
[0112] The thermoplastic polymer composition of the present invention may optionally contain
additives as long as they are not detrimental to the object of the present invention,
such as other synthetic resins, other rubbers, antioxidants, heat stabilizers, UV
absorbents, weathering stabilizers, antistatic agents, antislip agents, antiblocking
agents, nucleating agents, pigments, dyes, slip agents, hydrochloric acid absorbents
and copper inhibitors.
[0113] The addition amounts of such other synthetic resins, other rubbers, additives and
the like are not particularly limited as long as not being detrimental to the object
of the present invention. The thermoplastic polymer composition in an exemplary preferred
embodiment contains the components (A), (B), (C), (D) and (E) in a total amount of
60 to 100% by mass, preferably 80% by mass to 100% by mass, and the rest in the thermoplastic
polymer composition is composed of the above other synthetic resins, other rubbers,
additives and like. Such components include polyolefin waxes such as polyethylene
wax and polypropylene wax, low-density polyethylene, middle-density polyethylene,
low-density polyethylene, LLDPE composed of a copolymer of ethylene and a C4-10 α-olefin,
ethylene elastomers and styrene elastomers.
[0114] The thermoplastic polymer composition of the present invention may be produced by
a known method. For example, the thermoplastic polymer composition may be obtained
by simultaneously or sequentially mixing the individual components placed in a Henschel
mixer, a V-blender, a tumbler mixer, a ribbon blender and the like and then melt kneading
the mixture with a monoaxiial extruder, multiaxial extruder such as a biaxial extruder,
a kneader, a Banbury mixer and the like.
[0115] Among these, the use of apparatus excellent in kneading performance such as a multiaxial
extruder, a kneader and a Banbury mixer can provide a high quality thermoplastic polymer
composition in which each component is dispersed with more uniformity. In any stage
of the production described above, other additives such as antioxidants may be added.
[0116] The order of adding the individual components is not particularly limited. When the
modified olefin polymer (E) is used in combination, a desirable order is such that
the propylene-based polymer (B), the propylene-based polymer (C) and the modified
olefin polymer (E) are previously melt kneaded, and the resultant product is melt
kneaded together with the other components, or such that part of these polymer components
and the whole of the filler (D) are melt kneaded to form master batches, and these
are melt kneaded. Thereby, a composition excellent in the balance among mechanical
strength, hardness, flexibility and heat resistance can be obtained.
Article
[0117] The article of the present invention comprises the thermoplastic polymer composition
as described above. The above thermoplastic polymer composition can be melt-molded
into various forms by known melt molding methods. The known melt molding methods include
extrusion molding, rotating molding, calender molding, injection molding, compression
molding, transfer molding, powder molding, blow molding and vacuum molding. The propylene
resin composition according to an embodiment of the present invention contains the
filler at high proportion and is excellent in the balance among mechanical strength,
flexibility and heat resistance. The thermoplastic polymer composition of the present
invention is widely applicable for articles having flame retardance, such as electric
wires and electric cables and building materials.
[0118] The article as described above may be a composite article formed with an article
composed of other materials, such as a laminate.
[0119] The article is excellent in the balance of properties, i.e. , maintaining mechanical
strength and being excellent in flexibility as well as in scratch resistance, and
therefore can be applied suitably for, e.g., the coating of electric wires and electric
cables including the use as an insulator of an electric wire and electric cable and
an electric wire and electric cable sheath, typified by the coating of optical fibers.
With the article of the present invention, in particular, an article such as a tubular
electric wire and electric cable can have improved scratch resistance. Thus, taking
advantage of its flexibility and its heat resistance, the article of the present invention
is suited for an electric wire and electric cable sheath and an electric wire and
electric cable coating for consumer and household devices such as a power cord.
[0120] The coating layers such as an insulator of an electric wire and electric cable and
an electric wire and electric cable sheath as described above are formed around electric
wires and electric cables by a known method e.g., extrusion molding.
[0121] Hereinafter, the present invention is described in greater detail based on Examples.
EXAMPLES
Components (A) to (E)
Ethylene/unsaturated ester copolymer (A)
Ethylene/vinyl acetate copolymer (EVA-1)
[0122] EVAFLEX EV40LX (product name, manufactured by DuPont-Mitsui Polychemicals Co., Ltd.),
vinyl acetate content: 41% by mass, MFR (measured in accordance with JIS K 7210-99,
at 190°C, under a load of 2.16 kg): 2 g/10 min
Ethylene/vinyl acetate copolymer (EVA-2)
[0123] EVAFLEX EV270 (product name, manufactured by DuPont-Mitsui Polychemicals Co. , Ltd.),
vinyl acetate content: 28% by mass, MFR (measured in accordance with JIS K 7210-99,
at 190°C, under a load of 2.16 kg): 1 g/10 min
Propylene-based polymer (B)
[0124] As an isotactic homopolypropylene (hereinafter, abbreviated as h-PP), a propylene/ethylene
copolymer (Tm: 160°C, melt flow rate (temperature 230°C, load: 2.16 kg): 3 g/10 min)
was used.
Propylene-based polymer (C)
(C-1) Propylene/1-butene copolymer (PBR)
[0125] A propylene/1-butene copolymer (MFR (temperature 230°C): 7 g/10 min, Tm: 75°C, 1-butene
content: 26 mol%, Mw/Mn: 2.1, crystallinity (WAXD method) : 28%) produced by a method
described in
WO 2004/87775 was used.
(C-2) Propylene/ethylene/1-butene copolymer (PBER)
[0126] A propylene/ethylene/1-butene random copolymer (MFR (temperature 230°C): 6.0 g/10
min, Tm: not observed, Ethylene content: 16 mol%, 1-butene content: 6 mol%, Mw/Mn:
2.0, Shore A hardness: 75, crystallinity (WAXD method): not higher than 5%, mm value:
90%) produced by a method described in
WO 2004/87775 was used.
(C-3) Propylene/ethylene copolymer (PER)
[0127] A propylene/ethylene copolymer (MFR (temperature 230°C): 3.0g/10min, Tm: 46°C and
109°C, Ethylene content: 22 mol%, Mw/Mn: 2.1, Shore A hardness: 67) was used.
Filler (D)
(D-1) Magnesium hydroxide (Mg(OH)2)
[0128] Magnifin H5IV (product name, (Mg(OH)
2) manufactured by Albemarle Corporation) was used. Average particle diameter d
50 = 1.6 to 2.0 micrometer (µm)
(D-2) Organic phosphinic acid salt
[0129] Exolit OP1230 (product name, organic phosphinic acid salt manufactured by Clariant)
was used.
(D-3) Ammonium polyphosphate (APP)
[0130] Exolit AP462 (product name, ammonium polyphosphate (APP) manufactured by Clariant)
was used.
(D-4) Si powder
[0131] DC4-7081 (product name, Si powder manufactured by Dow Corning Toray Co., Ltd.) was
used.
[0132] Si powder serves as a flame retardance imparting agent and as a molding assistant
(slip agent).
Modified olefin polymer (E)
[0133] Using the following ethylene/1-butene copolymer (E-1) produced with a metallocene
catalyst, a maleic anhydride graft-modified ethylene/1-butene copolymer (E-2) was
produced.
(E-1) Ethylene/1-butene copolymer (EBR)
[0134] An ethylene/1-butene copolymer (density: 870 kg/m
3, MFR (190°C): 0.5 g/10 min, Mw/Mn: 2.1)
(E-2) Graft-modified ethylene/1-butene copolymer (acid-modified EBR)
[0135] 10 kg of the ethylene/1-butene copolymer (E-1) and a solution obtained by dissolving
50 g of maleic anhydride and 3 g of di-tert-butyl peroxide in 50 g of acetone were
blended in a Henschel mixer.
[0136] The resultant blended product was introduced into a hopper of a monoaxial extruder
having a screw diameter of 40 mm and L/D of 26, and was extruded into a strand at
a resin temperature of 260°C and an extruded amount of 6 kg/h. The strand was water-coold
and pelletized to provide a maleic anhydride graft-modified ethylene/1-butene copolymer
(E-2).
[0137] From the resultant acid-modified ethylene/1-butene copolymer (E-2), unreacted maleic
anhydride was extracted with acetone to measure a maleic anhydride graft amount in
this copolymer. As a result, the graft amount was found to be 0.43% by mass.
Measurement methods of property values
[0138] Property values were measured as follows.
(1) Comonomer (ethylene and 1-butene) contents and mmmm (stereoregularity pentad isotacticity)
[0139] Comonomer contents and mmmm were determined by
13C-NMR spectrum analysis.
(2) Melt flow rate (MFR)
[0140] Melt flow rate of the ethylene/unsaturated ester copolymer (A) was measured at 190°C
under a load of 2.16 kg in accordance with JIS K 7210-99.
[0141] Melt flow rate for the other polymers was measured at a temperature of 190°C or 230
°C under a load of 2.16 kg in accordance with ASTM D-1238.
(3) Melting point (Tm)
[0142] DSC exothermic and endothermic curves were determined, and a temperature at a top
of the melting peak that had ΔH in heating of not less than 1 J/g was defined as Tm.
This measurement was performed such that a sample was put in an aluminum pan and was
heated at 100°C/min to 200°C, kept at 200°C for 5 minutes, and then cooled at 10°C/min
to -150°C and thereafter heated at 10°C/min to 200°C; the exothermic and endothermic
curves obtained at this time was used for the measurement.
(4) Molecular weight distribution (Mw/Mn)
[0143] Molecular weight distribution (Mw/Mn) was measured by GPC (gel permeation chromatography).
The measurement was performed with the use of an orthodichlorobenzene solvent at a
temperature of 140°C.
(5) Density
[0144] Density was measured in accordance with a method described in ASTM D 1505.
(6) Crystallinity
[0145] Crystallinity was determined by analysis of wide-angle X-ray profile obtained from
a measurement using RINT2500 (manufactured by Rigaku Corporation) as a measurement
apparatus, and CuKα as an X-ray source.
(7) Intrinsic viscosity [η]
[0146] An Ubbelohde viscometer was used. A polymer sample was dissolved in decalin and a
viscosity of the solution was measured at a temperature of 135°C. From a value thus
measured, an intrinsic viscosity was determined.
(8) Tensile strength at break, Elongation at break, Initial tensile modulus (Young's
modulus)
[0147] In accordance with ASTM D638, a sheet of 2 mm in thickness was prepared with a press
molding machine and this sheet was tested to measure breaking strength (TS), elongation
at break (EL) and initial tensile modulus.
(9) Shore A hardness
[0148] In accordance with ASTM D2240, a sheet of 2 mm in thickness was prepared with a press
molding machine, and this sheet was tested with an A-type measurement device and a
scale was read immediately after the contact of an indenter.
(10) Shore D hardness
[0149] In accordance with ASTM D2240, a sheet of 2 mm in thickness was prepared with a press
molding machine, and this sheet was tested with a D-type measurement device and a
scale was read 5 seconds after the contact of an indenter.
(11) Limiting oxygen index (LOI)
[0150] In accordance with JIS K7201-2, a sheet of 2 mm in thickness was prepared with a
press molding machine, and this sheet was tested to measure limiting oxygen index.
Limiting oxygen index was used as an indicator of flame retardance.
(12) Thermal deformation
[0151] In accordance with JIS C3005, a sheet of 2 mm in thickness was prepared with a press
molding machine, and this sheet was was used for measurement performed under predetermined
conditions (90°C, 30min). Thermal deformation rato was used as an indicator of heat
resistance.
(13) TMA softening temperature
[0152] A pressure of 2 kg/cm
2 was applied to a planar indentor of 1.8 mm in diameter with heating at a heating
rate of 5°C/min, to measure a displacement (penetration depth). A temperature at the
time when the penetration depth reached 500 µm was defined as a softening temperature.
The softening temperature was used as an indicator of heat resistance.
(14) Vertical flame test (UL VW-1 test)
[0153] In accordance with UL 1580 standard, an article in the shape of an electric wire
and electric cable was subjected to a vertical flame test (UL VW-1 test). The test
result was used as an indicator of flame retardance.
Examples 1 to 12 and Comparative Examples 1 to 7
[0154] A composition with a formulation indicated in Table 1 was kneaded with a Labo Plastomill
manufactured by TOYO SEIKI Co., Ltd.
[0156] In the embodiments using EVA having a vinyl acetate content of 41% but not using
h-PP and PBER or PBR in combination as a polymer component (Comparative Example 1
and Comparative Example 2), the thickness loss ratio in heating deformation is high
and thus heat resistance is insufficient. In the embodiment not using PBER or PBR
in combination (Comparative Example 3) and in the embodiment not using EVA in combination
(Comparative Example 4), flexibility and elongation at break are insufficient. By
contrast, in the embodiments using EVA, h-PP and PBER in combination (Examples 1 to
6), articles excellent in the balance among flexibility, mechanical strength, elongation
at break, heat resistance and flame retardance can be obtained.
[0157] In the embodiments using EVA having a vinyl acetate content of vinyl acetate content
of 28% by mass but not using h-PP and PBER, PER or PBR as a polymer component in combination
(Comparative Example 5 and Comparative Example 6), heat resistance is insufficient.
In the embodiment not using PBER, PER or PBR in combination (Comparative Example 7),
flexibility and elongation at break are insufficient. By contrast, in the embodiments
using EVA, h-PP and PBER or PER in combination (Examples 7 to 12), articles excellent
in the balance among flexibility, mechanical strength, elongation at break, heat resistance
and flame retardance can be obtained.
Examples 13 to 16 and Comparative Examples 8 and 9
[0158] A composition with a formulation indicated in Table 2 was melt kneaded with a biaxial
extruder having a screw diameter of 32 mm, L/D of 42) to give a corresponding resin
compound. At this time, attention was paid to make sure that the resin temperature
was not higher than 230°C.
[0159] Using an electric wire and electric cable coater, a copper core wire and cable (manufactured
by Musashikinsen, 0.18 mm in diameter, 30-ply, pitch: 13, right-handed twining, outer
diameter: 1.2 mm) was coated with the compound obtained, to provide an electric wire
and electric cable (outer diameter: 4.0 mm).
[0160] The results of the property value measurement are set forth in Table 2. The electric
wires and electric cables of Examples 14 and 15 passed the UL VW-1 test.
[0161] [Table 2]
Table 2
Item |
|
PHOS-10 |
PHOS-11 |
PHOS-12 |
PHOS-13 |
PHOS-14 |
PHOS-12-2 |
unit |
Comp. Ex.8 |
Comp. Ex.9 |
Ex. 13 |
Ex. 14 |
Ex. 15 |
Ex. 16 |
Composition |
EVA-2 |
wt% |
100 |
80 |
80 |
80 |
80 |
80 |
h-PP |
wt% |
|
20 |
11 |
11 |
11 |
11 |
PBER |
wt% |
|
|
9 |
9 |
9 |
9 |
Organic phosphinic acid salt OP1230 |
phr |
40 |
40 |
20 |
40 |
60 |
|
Ammonium polyphosphate AP462 |
phr |
|
|
|
|
|
20 |
Si powder DC4-7081 |
phr |
5 |
5 |
5 |
5 |
5 |
5 |
Tensile test |
Tensile strength at break |
MPa |
13 |
8.8 |
15 |
12 |
8.9 |
16 |
Elongation at break |
% |
710 |
420 |
640 |
580 |
510 |
680 |
Initial tensile modulus |
MPa |
42 |
120 |
48 |
81 |
110 |
37 |
INDUSTRIAL APPLICABILITY
[0162] The thermoplastic polymer composition of the present invention is also capable of
containing fillers at a high proportion, and is excellent in the balance among mechanical
strength, flexibility and heat resistance. Further, the thermoplastic polymer composition
of the present invention is widely applicable for flame-retardant articles such as
electric wires and electric cables and building materials.
[0163] When the thermoplastic polymer composition according to the present invention is
applied for an insulating layer of an electric wire and electric cable sheath and
for an electric wire and electric cable coating, the article according to the present
invention is an electric wire and electric cable sheath and/or a coating layer. The
electric wire and electric cable sheath and the coating layer are formed around electric
wires and electric cables by a known method such as extrusion molding method.
[0164] The present invention can provide a thermoplastic polymer composition that is both
highly flame-retardant and is flexible, and can provide articles thereof.
[0165] The thermoplastic polymer composition according to the present invention has advantageous
effects as described above, and thus are suited for various articles such as electric
wire and electric cable coating, tapes, films, flame-retardant sheets, pipes, blow-molded
articles, flame-retardant wall paper, particularly suited for an electric wire and
electric cable sheath and an insulator of an electric wire and electric cable and
an electric wire and electric cable coating. In particular, taking advantage of its
flexibility and its heat resistance, the thermoplastic polymer composition according
to the present invention is used suitably for an electric wire and electric cable
sheath and an electric wire and electric cable coating for consumer and household
devices such as a power cord.